Here is a remotely controlled power strip with a wireless remote:
https://www.amazon.com/dp/B001Q9EFUK/ref=sspa_dk_detail_3?psc=1&pd_rd_i=B001Q9EFUK&pd_rd_wg=1Nmie&pd_rd_r=0TQHXZ7RR47DJAKKE4Y5&pd_rd_w=oeXU2

You can mount the remote behind a panel with straps, and have a slot in the panel for your guests to push the button to start it.

Here is a programmable AC timer to plug into the above remote:
https://www.amazon.com/gp/product/B008999S3O/ref=ask_ql_qh_dp_hza

The timer looks to have a manual 'on' switch, in which case you would not need the above remote.

Larry